State Highlights

Voters also approved three ballot initiatives, including one that put a limit on interest rates for payday loans.

Despite his affiliation with the ruling party in Congress, Mr. McDonald sought to capitalize on anti-incumbent sentiments this year by portraying Mr. Rehberg, who has held the seat for 10 years, as a political insider. Mr. McDonald, a rancher and the former chairman of the state’s Democratic Party, also questioned Mr. Rehberg’s involvement in a boating accident last summer that resulted in serious injuries, and in charges that the driver, a state senator, had been drinking.

For their part, Republicans sought to link Mr. McDonald, a former lawyer, to an organized-crime figure and mob informant that he once represented.

Mr. McDonald, in addition to the typical television commercials and rallies, tried to attract attention to his long-shot campaign: he often showed up at campaign events atop his horse, Rowboat, and with a donkey, Justice, in tow.